A telecommunications network can be viewed as consisting of three main sections: the backbone network, the metro network and the access network. The backbone network connects major switching centers typically located in major cities. The metro network connects a backbone switching center to smaller switching centers located within a metropolitan area, i.e. within a city. The access network connects end user customers to the switching centers of the metro network.
In the backbone the traffic of tens of thousands to millions of customers is aggregated (multiplexed) onto the optical transport equipment that forms the interconnections between switching centers. The cost per customer traffic flow is therefore low due to the amortization of the high equipment costs across the large number of flows. The metro network carries the traffic of hundreds to thousands of customers. The cost per customer flow is higher than in the backbone because the cost of the transport equipment is amortized over a smaller number of flows. The access network connects a very small number of customers or often a single customer to the metro switching centers. The transport equipment used to make these customer connections is typically the same as that used in the metro network. The cost of the access transport is thus amortized over a small number or single customer traffic flow.
The dominant optical transport technology is Synchronous Optical Networking (SONET) in North America, or Synchronous Digital Hierarchy (SDH) elsewhere. The service providers who operate these networks have operational support systems (OSS) that are used to provision, monitor, diagnose and control their transport network. These OSS systems range in size or complexity dependant upon the operators environment, ranging from individual element manager systems addressing one or more of the major management disciplines—Fault, Configuration, Accounting, Performance, Security—(FCAPS), to highly integrated systems providing tight coupling and interdependence across these roles. These OSS systems are designed to use familiar, consistent data retrieved and recorded from the transport network, predominantly based on standard SONET/SDH metrics. Equipment that does not provide performance data in the formats required by these OSS, and hence does not readily integrate, represents an added cost to the service providers.